Phytoestrogens show potential as a treatment for menopausal women with late-onset asthma that may relieve symptoms of both conditions, according to a new review.
and the absence of these hormones during childhood and menopause has been associated with fewer and less severe asthma episodes, wrote Bettina Sommer, PhD, of the Instituto Nacional de Enfermedades Respiratorias, Mexico City, and colleagues.
Late-onset asthma (LOA) has been categorized as a specific asthmatic phenotype that includes menopausal women, and research is needed to explore therapeutic alternatives that might provide relief to older women suffering from LOA, they said.
In a review published in the International Journal of Molecular Sciences, the researchers outlined the potential of phytoestrogens to manage LOA as well as symptoms of menopause.
LOA is often nonatopic and distinguished by a lack of eosinophilic inflammation; it is also associated with obesity and pollutants such as cigarette smoke. LOA is more common in women versus men, and develops between ages 27 and 65 years, the researchers wrote. Very late-onset asthma, which develops in women aged 65 years and older, is related to low levels of total lack of circulating estrogens.
Previous studies have shown that hormone therapy reduces the risk of LOA in menopausal women, but concerns about side effects persist. Phytochemicals offer a low-risk alternative, but phytoestrogen-based hormone therapy and its role in LOA have not been well studied, the researchers wrote.
Estrogen receptors (ERs) have two intracellular isoforms, alpha and beta. “Notably, the literature sustains that ERs expression differs between asthmatics and nonasthmatics,” and mainly the beta ERs are up-regulated in asthma or during inflammations, the researchers said. Phytoestrogens activate ER and benefit postmenopausal women, especially those with asthma, in addition to their anti-inflammatory and antioxidant properties.
Studies using mouse models have shown that E2 phytoestrogen supplementation in mice both increases the expression of antioxidant enzymes and reduces inflammation, according to the researchers. Age-related changes in hormonal statues, immunology, and systemic inflammation may predispose older adults to more infections and asthma exacerbations, but also might drive the development of LOA.
As another example of potential connections between phytoestrogen and asthma, phytoestrogen’s action on an estrogen receptor, notably the beta-ER, was associated with lowered airway hyperresponsiveness in a mouse model, and beta-ER knockout mice showed reduced lung function, compared with wild-type and alpha-ER knockout mice.
More research is needed, but novel therapies using phytoestrogens offer an added advantage to older women with LOA by potentially easing some menopause symptoms with fewer side effects than other options, the researchers wrote. “They may also contribute to more efficient responses to infection and inflammation leading menopausal women to a much better quality of life.”
The study was funded by the Instituto Nacional de Enfermedades Respiratorias, Consejo Nacional de Ciencia y Tecnología, Programa de Apoyo a Proyectos de Investigación e Innovación Tecnológica, and the Universidad Nacional Autonoma de Mexico. The researchers had no financial conflicts to disclose.